1. Technical Field of the Invention
The present invention relates to a boiling and condensing apparatus for cooling a heating element by the transferring of latent heat due to the boiling and condensation of a coolant.
2. Description of the Related Art
Various proposals have been made by the applicant of this patent application in relation to boiling and condensing apparatuses. One such boiling and condensing apparatuses includes a coolant tank, a bottom of which is brought into contact with a heating element such as heat-generating electronic parts to receive heat from the latter, a plurality of tubes arranged upright on the upper surface of the coolant tank to be communicated with the interior of the coolant tank, and a header tank for communicating the plurality of tubes with each other.
In this prior art, the coolant tank has a heat-reception plate, on which surface is attached the heating element, a heat-radiation plate, on which surface are attached the tubes, and two intermediate plates laminated to each other and disposed between the heat-reception plate and the heat-radiation plate so that a plurality of slit-like openings thereof extend through the thickness of the plates. One example of such an arrangement of the plate members used in the coolant tank of the laminated structure is shown in FIG. 6, and a sectional view of the boiling and condensing apparatus provided with this coolant tank is shown in FIGS. 7A and 7B.
An intermediate plate 124 shown in FIG. 6 is adjacent to a heat-radiation plate 125 having openings 125a for attaching the tubes. As shown in the drawing, a plurality of slit-like openings 124a extending in the lateral direction in the drawing are arranged in parallel to each other in the intermediate plate 124. Also, the intermediate plate 122 shown in FIG. 6 is adjacent to the heat-reception plate 121. As shown in the drawing, the intermediate plate 122 has a plurality of slit-like openings 122a extending parallel to each other in the vertical direction in the drawing.
When the intermediate plates 122, 124 are laminated between the heat-reception plate 121 and the heat-radiation plate 125, the slit-like openings 122a and 124a are disposed vertical to each other. Thereby, all the openings 122a and 124a are communicated with each other to form a space for storing the coolant in the coolant tank.
In this regard, a boiling area is defined by a portion of the attachment surface in the interior of the coolant tank on which the heating element is projected in the vertical direction, wherein the coolant is vaporized by receiving heat from the heating element. The boiling area is enclosed by a chain line in FIG. 6 and indicated as 161.
A boiling and condensing apparatus 101 having a coolant tank 102 formed by laminating the plates 121, 122, 124 and 125 to each other is disposed so that the coolant tank 102 is positioned on the lower side as shown in FIG. 7A. When the heating element 6 attached to the outer bottom surface of the coolant tank 102 is cooled (i.e., when used in a bottom-heat mode), the coolant stored in the coolant tank 102 receives heat from the heating element 6 and is boiled mainly in the boiling area 161.
The coolant vaporized to become a gas passes through tubes 103 mainly disposed above the boiling area 161, then passes through the interior of a header tank 104 and finally returns to the outer peripheral region of coolant tank 102 via the tubes 103 mainly disposed above the non-boiling area. At this time, the coolant in the tubes 103 radiates the latent heat outside and is condensed to a liquid coolant.
In the boiling and condensing apparatus, however, the coolant tank 102 is arranged on a lateral side as shown in FIG. 7B. When the heating element 6 attached to the outer lateral surface of the coolant tank 102 is cooled (that is, when used in a side-heat mode), the coolant flows through a path different from that in a so-called bottom-heat mode shown in FIG. 7A.
When the coolant stored in the coolant tank 102 is boiled mainly in the boiling area by receiving heat from the heating element 6, the vaporized coolant passes through the upper tubes 103 as shown in FIG. 7B, enters the header tank 104, and returns to the coolant tank 102 via the lower tubes 103. At this time, in the tubes 103, the coolant radiates the latent heat outside and is condensed to a liquid coolant.
Under the circumstances, part of the coolant boiled in the coolant tank 102 may flow in the counter direction within the coolant tank 102 or in the tubes 103 and interfere with the normal flow of the coolant. If the circulation of the coolant is not smoothly carried out in such a manner, there might be a problem in that the quenching performance is lowered.
The present invention has been made to solve the above-mentioned problems in the prior art by providing a boiling and condensing apparatus facilitating the circulation of coolant even if the coolant tank is disposed on the lateral side so that the apparatus is used in a side-heat mode wherein the heating element attached to the lateral outer surface of the coolant tank is quenched.
To achieve the above object, according to one aspect of the present invention, a boiling and condensing apparatus is provided which comprises a coolant tank storing coolant to be boiled by receiving heat from a heating element attached to one surface of the coolant tank, a radiator having a plurality of tubes communicated with the interior of the coolant tank and substantially standing upright from the other surface disposed opposite to the surface in the coolant tank on which the heating element is attached, and a header tank communicating the plurality of tubes with each other, wherein the coolant stored in the coolant tank receives heat from the heating element and is boiled to vaporize into a coolant vapor, from which a latent heat is radiated from the radiator to cool the heating element, wherein the plurality of tubes consists of first tubes for delivering the coolant from the coolant tank to the header tank and second tubes for delivering the coolant from the header tank to the coolant tank, a boiling area is formed in the interior of the coolant tank, for evaporating and vaporizing the coolant by the heating element, the coolant tank comprises a first coolant flow path for communicating the boiling area with the first tube, and a second coolant flow path for communicating the boiling area with the second tube, and the second coolant flow path is longer than the first coolant flow path and, when the heating element attachment surface is disposed on the lateral side, part of the second coolant flow path disposed beneath the boiling area is solely connected to the boiling area.
According to this apparatus, as the condensed liquid coolant is delivered to the boiling area solely from below via the second coolant flow path longer than the first coolant flow path, and the vaporized coolant in the coolant tank hardly flows in the reverse direction, in the second tube, to the second coolant flow path. Thus, it is possible to facilitate the coolant circulation.
Also, according to another aspect of the present invention, the boiling area is provided generally at a center of the interior of the coolant tank, and the second tube is assembled at a position outside the boiling area in the coolant tank.
Thus, as in the preceding aspect of the present invention, it is possible to easily form the second coolant flow path to be longer than the first coolant flow path and to connect the former to the boiling area solely from below.
In this case, when the heating element attachment surface is disposed on the lateral side, the second tube is assembled to the upper and lower sides on the coolant tank.
Also, according to the present invention, a plurality of second tubes are provided, and partitions are formed in the header tank so that the coolant is delivered approximately uniformly to the plurality of second tubes.
In this aspect, even if there are a plurality of second tubes, it is possible to facilitate the coolant circulation.
According to the present invention, the coolant tank is formed of a plurality of plate members laminated to each other.
In this aspect, as the plurality of plate members are laminated to each other, it is possible to easily form the coolant tank.
According to the present invention, the header tank is formed of a plurality of plate members laminated to each other.
In this aspect, it is possible to easily form the header tank by laminating the plurality of plate members with each other.
Also, according to the present invention, the radiator is provided with heat-radiation fins between the plurality of tubes.
In this aspect, it is possible to improve the heat-radiation performance of the radiator.
In a structure in which the resistance of the second coolant flow path is larger than that of the first coolant flow path, or the second coolant flow path detours around the boiling area, it is possible that the coolant vaporized in the boiling area hardly flows in reverse from the second coolant flow path in the direction of the second tube.
The present invention will be more clearly understood with reference to the attached drawing and an explanation of the preferred embodiments described hereinafter.